Development of Mn2+ Activated Ba-Sr-Mg-aluminate Green Phosphors for PDPs

BaAl12O19 is considered to be a mixture of a Ba-poor aluminate (0.82BaO·6Al2O3) and a Ba-rich aluminate (xBaO·6Al2O3, x=1.30±0.2). Because the Ba-poor aluminate and BaMgAl10O17 (BAM) have exactly the same crystal structure as β-alumina, both compounds form solid solutions with it. In this study, we prepared various kinds of solid solutions of the Ba-poor aluminate and BAM in which Mn2+ was substituted for some or all of the Mg2+. These formulae can be expressed as (1-α)(0.82BaO·6Al2O3)· α(BaMg1-βMnβAl10O17). Their emission properties under 146 nm excitation were studied. As α and β were changed with a constant Mn2+ content in the phosphor (α· β=0.12), two kinds of bright solid solutions were found. One was a BAM-poor solid solution (α=0.12, β=1.0) and the other was a BAM-rich solid solution (α=0.92, β=0.13). Substituting Sr2+ for Ba2+ improved the luminance of the BAM-rich solid solution. For example, the composition of a BAM-rich solid solution in which Sr2+ replaced 76% of the Ba2+ was Ba0.24Sr0.75Mg0.80Mn0.12Al10.2O17.21. Comparing the properties of this phosphor with those of the conventional BaAl12O19:Mn, we found the luminance was 18% higher, the chromaticity was purer green (x=0.146, y=0.749) and the 1/10 decay time was equivalent (14 ms). This material should serve as a new green phosphor for PDPs, though its lifetime in PDPs remains to be measured.